The present invention relates generally to the field of networking, and more particularly to resource access for virtual devices in a cluster having network-attached resources.
Conventional networked computing environments for deployment and migration of virtual servers with storage area network (SAN)-attached storage are set up as follows. A cluster of physical servers (PSs) is configured with a hypervisor such that each PS hosts multiple virtual machines, referred to herein as virtual servers (VSs). The VSs access SAN-attached storage devices via physical host bus adapters (HBAs) connected to the hosting PSs. The VSs are flexibly deployed on different PSs and can be migrated among the PSs within the PS cluster.
The PSs and storage devices are connected via SANs. A SAN may be made up of one or more switches, and may be based on a communications protocol such as Fibre Channel (FC), Fibre Channel over Ethernet (FCoE), Internet Small Computer System Interface (iSCSI), AT Attachment (ATA) over Ethernet (AoE), or HyperSCSI, to name a few. In the case of Fibre Channel, the PSs and storage controllers access an FC-SAN via the HBAs, where each HBA has a so-called World-Wide Port Name (WWPN) that is unique within the scope of the network. The FC-SAN-attached storage devices are identified by logical unit numbers (LUNs).
Access to the storage devices on the SAN is controlled via zoning and LUN masking. Zoning defines which ports are able to communicate, including the FC switch ports. LUN masking defines which HBAs can access a particular LUN, with each HBA identified according to its unique WWPN.
In a VS environment, the HBAs are conventionally virtualized such that each HBA represents one or more virtual HBAs (vHBAs). Many HBA virtualization techniques exist, including: (i) single root I/O virtualization (SR-IOV) (an extension to the Peripheral Component Interconnect Express (PCIe) standard); (ii) proprietary methods; and (iii) N_Port ID Virtualization (NPIV). N_Port ID Virtualization is a FC facility allowing multiple FC node port (N_Port) IDs to share a single physical N_Port. Among other advantages, NPIV allows multiple FC initiators to occupy a single physical port, easing hardware requirements in SAN design, especially in environments where virtual SANs are used.